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Old 20th January 2011, 02:12 PM   #1
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Default 35hz 120litre TH?

G'day,

I've many hours reading this forum, but perhaps someone could point me a design that has the following:

-F3 of approx 35hz
-120 litre approx external vol
-single 8" or 10" driver (preferably parts-express sourced)

Something in between William Cowans 60hz horn, Volvotreter's TB 6.5 TH, and the SS15. I'm not too keen on learning HORNRESP, I don't want to build my first tapped horn of my own design. I want to build someone else's design, then learn hornresp, then build my own design, and compare.

Thanks,
Randy
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Old 20th January 2011, 05:34 PM   #2
jwmbro is offline jwmbro  United States
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Hi, a few comments:

-You mention how low you want to go, but now how loud you want to go. This is a very important criterion. Just for fun I simulated a 16liter Tapped Pipe with a small 4" fullrange driver I have lying around. This design has a -3dB point at 35Hz, just like you are looking for. However, it only plays 93dB loud. Probably not what you were looking for....

-Hornresp is actually very easy to learn. Just take the input from an existing design on here, enter your driver parameters in the 6th and 7th row, and then hit tools --> loudspeaker wizard and play around. Even if you do build a proven design, you should at least try copying down the Hornresp inputs (assuming the designer publishes them) and at least have a look yourself at what the program predicts. Maybe just change around the Eg number to see how it plays at different power levels.

-You say you're looking for somebody else's design. Is this because the modeling in Hornresp scares you off, or because of the difficulties in folding, or maybe because you don't want to go through the whole building and prototyping process to compare if your model lines up with your simulations?
Because, there are actually not that many fully documented designs out there that have been simulated, folded, built, measured and compared - so you might not be able to find one that fits your criteria.

-However there are plenty of non built, but simulated designs. They should line up fairly well with the sims if you build them if you're willing to try that. I just took ten minutes to grab a random 10" dayton woofer specs from parts-express (first one I saw that looked promising, there may be better candidates - there's a lot of stuff on PE) and sim a quick T-TQWT for you. It's a simple single-fold design that will fit into a 25x30x102cm box (do canadians use metric? they seem to be the slightly less archaic version of americans, but if not, that's 10x12x40 inches), which is about 80 liters external. About 108dB, with a -3dB point at 35Hz. Have a look:

Click the image to open in full size.
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Old 20th January 2011, 05:45 PM   #3
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Your design looks quite promising indeed. A pair of them would be cool. My main reason for choosing someone else's design for my first build is because I want something to compare to. There will always be a nagging doubt how my own first design performs on a relative basis, unless I can compare side by side with one that was designed by someone with much more experience.
But I will get started with hornresp also.
I'll live whatever SPL 35hz-38hz/100-120L gives me. I know there's no free lunch.

Thanks for your design, I hope we'll be able to bang out a design over the few days, then I can start building it.
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Old 20th January 2011, 08:25 PM   #4
jbell is offline jbell  United States
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Ontario:

you question falls in that grey area of "not quite one or the other" in my mind.

It's not 40hz pa / music, and it's not DEEP for HT... D&B and dub in house is about all I can place for a 35hz requirement in only a 8" or 10" driver size.

regardless... I was bored this afternoon and gave this some thought.... How's a dayton titanic 10" TH mini sound? Flat to 30hz@130db in a corner, in your 120liter size requirement.

A bash 500 with the high pass resistor mod from stock 19hz to 30hz, and you have one REALLY serious home sub. No it's not flat to 10hz.... but it'll knock pictures off the wall, and it's low enough to be taken seriously watching movies.

is that kinda what you are looking for? or is that a little much for a trial run?
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File Type: jpg titanicTH.JPG (100.3 KB, 421 views)
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Old 20th January 2011, 10:34 PM   #5
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Wow, that's impressive!

What I want it for is music, and it might be a little more than I want I want for a first time project. Maybe not though. Should I just start running hornresp to figure out the box? Not sure what the numbers mean.

Now keep in mind I would be using a pair, and I have a Crown XLS2000 amp to drive, and would prefer to not present a 2 ohm load. The Dayton's are 4 ohm. What about the Tang 8" or 8x12"?

Why a pair? good question, I may want to use them for live use also, and If can get away with these acting as a stand for the main speakers, all the better (hence a pair). I currently have a B&C 18PS100 in a 5.2ft3 internal cab, (20" Sonotube), and it kicks, but I have the bug you know...

Thanks,
Randy
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Old 20th January 2011, 11:23 PM   #6
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Considering Volvotreter's Tang 6.5 38hz folded horn is 54 litre ext, 100-120 litres would be merrier wouldn't it?
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Old 21st January 2011, 04:33 AM   #7
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I do have a couple of Goldwood 10090's (90oz magnets!)

Goldwood GW-10090 10" Select Series PA Woofer | Parts-Express.com

Useful for this project?
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Old 21st January 2011, 05:28 AM   #8
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by ontariomaximus View Post
I do have a couple of Goldwood 10090's (90oz magnets!)

Goldwood GW-10090 10" Select Series PA Woofer | Parts-Express.com

Useful for this project?
That will actually do quite well in the design suggested by jbell, getting you about 122dB in a corner, with a -3dB point at 30Hz, which is a bit lower than you were after. It is however 125l internal, which by my rough guestimate puts you at almost 200l external, at least compared to some other designs. By my very rough guess you could get away with around 80l internal in keeping with your 120l external design constraints. I tried to shrink it up a little for a 75l design to get 122dB in corner but only with 35Hz as a -3dB point, have a look:
Click the image to open in full size.

Bear in mind all these tapped designs here will definitely need a ~30Hz highpass, and also if you really want to know what you're building you should at least get a basic grasp of HornResp.

Here's what I did, I read this tutorial, it was very helpful.

Or, my suggestion for you would be to play around with some existing designs like jbell's and mine. Here's a real quick runup if you look at hornresp, it's 9 lines of 4 (sometimes 3) input boxes. Either enter by double clicking boxes or by entering a number.

Line 1: Various environmental parameters. Relevant for you are Ang (0.5 if the box is in a corner, 2.0 if it's on the ground with no walls - 2.0 is what corresponds to most other programs - 0.5 will show up a low louder) and Eg - Eg is the input voltage, either change this manually, or double click on it to enter a wattage - if you're more familiar with wattage).
Lines 2-5: Shape of the horn. The S values are crosssections, the L (or sometimes Par or Con or Exp - change this by double clicking the word, you want to keep it on Par as a beginner) sections are the length between the crosssection. The easiest way to figure this stuff out is to just copy someone's done design, and go to Tools --> Loudspeaker Wizard and adjust these with the slider, viewing what it actually changes on a diagram of the speaker.
Lines 6-7: Parameters of the driver (and shape of the box - the bottom right one here should say TH - 1 for now) which can be obtained from spec sheets - or if the driver is not listed in the spec sheet, double click the box and it will offer you to enter different more available parameters and calculate the necessary ones itself.
Lines 8-9: These should all read 0 for tapped horns... they're for designing things like closed boxes, front loaded horns, vented boxes... play around with these whenever you feel like it, but it's not necessary to understand the designs in this thread.

Once you have a design set up, hit calculate, and then go to Window --> Whichever simulation result you want. Or just view it in the Loudspeaker Wizard.
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Old 21st January 2011, 04:17 PM   #9
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I just started with hornresp and here is my first attempt with the Goldwood 10090. Can you critique?
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File Type: jpg GW 10090.jpg (97.2 KB, 340 views)
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Old 21st January 2011, 10:17 PM   #10
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Quote:
Originally Posted by ontariomaximus View Post
I just started with hornresp and here is my first attempt with the Goldwood 10090. Can you critique?

Why are you setting Rg @1.10? Bad speaker cables?

Good choice modelling in 2PI space first though. Easier to compare the results of your HR models with simple sealed and vented models from other design programs.
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